Normally it is required that the forces acting on the gate operating ring of a horizontal turbine machine be equally distributed. However, there has been a demand for a counterweight arrangement for providing a closing force if fluid pressure to the gate ring operator of a bulb turbine is lost. In providing an effective counterweight for the gate ring, the large weight destroys the equal distribution of forces on the particular gate operating ring.
Turbine machine size has increased with a corresponding increase in the size of the gate operating ring having a much larger radius. Thus, a greater unequal distribution of forces are applied to the bulb turbine gate ring. The greater unequal distribution of forces upon the gate ring requires that gate ring servomotors must be oversized to counteract the increase in the weight of the counterweight in an opening movement.